1 //! Code that is useful in various codegen modules.
3 use crate::consts::{self, const_alloc_to_llvm};
4 pub use crate::context::CodegenCx;
5 use crate::llvm::{self, BasicBlock, Bool, ConstantInt, False, OperandBundleDef, True};
6 use crate::type_::Type;
7 use crate::type_of::LayoutLlvmExt;
8 use crate::value::Value;
10 use rustc_ast::Mutability;
11 use rustc_codegen_ssa::mir::place::PlaceRef;
12 use rustc_codegen_ssa::traits::*;
13 use rustc_hir::def_id::DefId;
14 use rustc_middle::bug;
15 use rustc_middle::mir::interpret::{ConstAllocation, GlobalAlloc, Scalar};
16 use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
17 use rustc_middle::ty::TyCtxt;
18 use rustc_session::cstore::{DllCallingConvention, DllImport, PeImportNameType};
19 use rustc_target::abi::{self, AddressSpace, HasDataLayout, Pointer, Size};
20 use rustc_target::spec::Target;
22 use libc::{c_char, c_uint};
27 * A note on nomenclature of linking: "extern", "foreign", and "upcall".
29 * An "extern" is an LLVM symbol we wind up emitting an undefined external
30 * reference to. This means "we don't have the thing in this compilation unit,
31 * please make sure you link it in at runtime". This could be a reference to
32 * C code found in a C library, or rust code found in a rust crate.
34 * Most "externs" are implicitly declared (automatically) as a result of a
35 * user declaring an extern _module_ dependency; this causes the rust driver
36 * to locate an extern crate, scan its compilation metadata, and emit extern
37 * declarations for any symbols used by the declaring crate.
39 * A "foreign" is an extern that references C (or other non-rust ABI) code.
40 * There is no metadata to scan for extern references so in these cases either
41 * a header-digester like bindgen, or manual function prototypes, have to
42 * serve as declarators. So these are usually given explicitly as prototype
43 * declarations, in rust code, with ABI attributes on them noting which ABI to
46 * An "upcall" is a foreign call generated by the compiler (not corresponding
47 * to any user-written call in the code) into the runtime library, to perform
48 * some helper task such as bringing a task to life, allocating memory, etc.
52 /// A structure representing an active landing pad for the duration of a basic
55 /// Each `Block` may contain an instance of this, indicating whether the block
56 /// is part of a landing pad or not. This is used to make decision about whether
57 /// to emit `invoke` instructions (e.g., in a landing pad we don't continue to
58 /// use `invoke`) and also about various function call metadata.
60 /// For GNU exceptions (`landingpad` + `resume` instructions) this structure is
61 /// just a bunch of `None` instances (not too interesting), but for MSVC
62 /// exceptions (`cleanuppad` + `cleanupret` instructions) this contains data.
63 /// When inside of a landing pad, each function call in LLVM IR needs to be
64 /// annotated with which landing pad it's a part of. This is accomplished via
65 /// the `OperandBundleDef` value created for MSVC landing pads.
66 pub struct Funclet<'ll> {
67 cleanuppad: &'ll Value,
68 operand: OperandBundleDef<'ll>,
71 impl<'ll> Funclet<'ll> {
72 pub fn new(cleanuppad: &'ll Value) -> Self {
73 Funclet { cleanuppad, operand: OperandBundleDef::new("funclet", &[cleanuppad]) }
76 pub fn cleanuppad(&self) -> &'ll Value {
80 pub fn bundle(&self) -> &OperandBundleDef<'ll> {
85 impl<'ll> BackendTypes for CodegenCx<'ll, '_> {
86 type Value = &'ll Value;
87 // FIXME(eddyb) replace this with a `Function` "subclass" of `Value`.
88 type Function = &'ll Value;
90 type BasicBlock = &'ll BasicBlock;
91 type Type = &'ll Type;
92 type Funclet = Funclet<'ll>;
94 type DIScope = &'ll llvm::debuginfo::DIScope;
95 type DILocation = &'ll llvm::debuginfo::DILocation;
96 type DIVariable = &'ll llvm::debuginfo::DIVariable;
99 impl<'ll> CodegenCx<'ll, '_> {
100 pub fn const_array(&self, ty: &'ll Type, elts: &[&'ll Value]) -> &'ll Value {
101 unsafe { llvm::LLVMConstArray(ty, elts.as_ptr(), elts.len() as c_uint) }
104 pub fn const_vector(&self, elts: &[&'ll Value]) -> &'ll Value {
105 unsafe { llvm::LLVMConstVector(elts.as_ptr(), elts.len() as c_uint) }
108 pub fn const_bytes(&self, bytes: &[u8]) -> &'ll Value {
109 bytes_in_context(self.llcx, bytes)
112 pub fn const_get_elt(&self, v: &'ll Value, idx: u64) -> &'ll Value {
114 assert_eq!(idx as c_uint as u64, idx);
115 let r = llvm::LLVMGetAggregateElement(v, idx as c_uint).unwrap();
117 debug!("const_get_elt(v={:?}, idx={}, r={:?})", v, idx, r);
124 impl<'ll, 'tcx> ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
125 fn const_null(&self, t: &'ll Type) -> &'ll Value {
126 unsafe { llvm::LLVMConstNull(t) }
129 fn const_undef(&self, t: &'ll Type) -> &'ll Value {
130 unsafe { llvm::LLVMGetUndef(t) }
133 fn const_int(&self, t: &'ll Type, i: i64) -> &'ll Value {
134 unsafe { llvm::LLVMConstInt(t, i as u64, True) }
137 fn const_uint(&self, t: &'ll Type, i: u64) -> &'ll Value {
138 unsafe { llvm::LLVMConstInt(t, i, False) }
141 fn const_uint_big(&self, t: &'ll Type, u: u128) -> &'ll Value {
143 let words = [u as u64, (u >> 64) as u64];
144 llvm::LLVMConstIntOfArbitraryPrecision(t, 2, words.as_ptr())
148 fn const_bool(&self, val: bool) -> &'ll Value {
149 self.const_uint(self.type_i1(), val as u64)
152 fn const_i16(&self, i: i16) -> &'ll Value {
153 self.const_int(self.type_i16(), i as i64)
156 fn const_i32(&self, i: i32) -> &'ll Value {
157 self.const_int(self.type_i32(), i as i64)
160 fn const_u32(&self, i: u32) -> &'ll Value {
161 self.const_uint(self.type_i32(), i as u64)
164 fn const_u64(&self, i: u64) -> &'ll Value {
165 self.const_uint(self.type_i64(), i)
168 fn const_usize(&self, i: u64) -> &'ll Value {
169 let bit_size = self.data_layout().pointer_size.bits();
171 // make sure it doesn't overflow
172 assert!(i < (1 << bit_size));
175 self.const_uint(self.isize_ty, i)
178 fn const_u8(&self, i: u8) -> &'ll Value {
179 self.const_uint(self.type_i8(), i as u64)
182 fn const_real(&self, t: &'ll Type, val: f64) -> &'ll Value {
183 unsafe { llvm::LLVMConstReal(t, val) }
186 fn const_str(&self, s: &str) -> (&'ll Value, &'ll Value) {
187 let str_global = *self
193 let sc = self.const_bytes(s.as_bytes());
194 let sym = self.generate_local_symbol_name("str");
195 let g = self.define_global(&sym, self.val_ty(sc)).unwrap_or_else(|| {
196 bug!("symbol `{}` is already defined", sym);
199 llvm::LLVMSetInitializer(g, sc);
200 llvm::LLVMSetGlobalConstant(g, True);
201 llvm::LLVMRustSetLinkage(g, llvm::Linkage::InternalLinkage);
207 let cs = consts::ptrcast(
209 self.type_ptr_to(self.layout_of(self.tcx.types.str_).llvm_type(self)),
211 (cs, self.const_usize(len as u64))
214 fn const_struct(&self, elts: &[&'ll Value], packed: bool) -> &'ll Value {
215 struct_in_context(self.llcx, elts, packed)
218 fn const_to_opt_uint(&self, v: &'ll Value) -> Option<u64> {
219 try_as_const_integral(v).map(|v| unsafe { llvm::LLVMConstIntGetZExtValue(v) })
222 fn const_to_opt_u128(&self, v: &'ll Value, sign_ext: bool) -> Option<u128> {
223 try_as_const_integral(v).and_then(|v| unsafe {
224 let (mut lo, mut hi) = (0u64, 0u64);
225 let success = llvm::LLVMRustConstInt128Get(v, sign_ext, &mut hi, &mut lo);
226 success.then_some(hi_lo_to_u128(lo, hi))
230 fn zst_to_backend(&self, _llty: &'ll Type) -> &'ll Value {
231 self.const_undef(self.type_ix(0))
234 fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, llty: &'ll Type) -> &'ll Value {
235 let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() };
237 Scalar::Int(int) => {
238 let data = int.assert_bits(layout.size(self));
239 let llval = self.const_uint_big(self.type_ix(bitsize), data);
240 if layout.primitive() == Pointer {
241 unsafe { llvm::LLVMConstIntToPtr(llval, llty) }
243 self.const_bitcast(llval, llty)
246 Scalar::Ptr(ptr, _size) => {
247 let (alloc_id, offset) = ptr.into_parts();
248 let (base_addr, base_addr_space) = match self.tcx.global_alloc(alloc_id) {
249 GlobalAlloc::Memory(alloc) => {
250 let init = const_alloc_to_llvm(self, alloc);
251 let alloc = alloc.inner();
252 let value = match alloc.mutability {
253 Mutability::Mut => self.static_addr_of_mut(init, alloc.align, None),
254 _ => self.static_addr_of(init, alloc.align, None),
256 if !self.sess().fewer_names() {
257 llvm::set_value_name(value, format!("{:?}", alloc_id).as_bytes());
259 (value, AddressSpace::DATA)
261 GlobalAlloc::Function(fn_instance) => (
262 self.get_fn_addr(fn_instance.polymorphize(self.tcx)),
263 self.data_layout().instruction_address_space,
265 GlobalAlloc::VTable(ty, trait_ref) => {
268 .global_alloc(self.tcx.vtable_allocation((ty, trait_ref)))
270 let init = const_alloc_to_llvm(self, alloc);
271 let value = self.static_addr_of(init, alloc.inner().align, None);
272 (value, AddressSpace::DATA)
274 GlobalAlloc::Static(def_id) => {
275 assert!(self.tcx.is_static(def_id));
276 assert!(!self.tcx.is_thread_local_static(def_id));
277 (self.get_static(def_id), AddressSpace::DATA)
281 llvm::LLVMRustConstInBoundsGEP2(
283 self.const_bitcast(base_addr, self.type_i8p_ext(base_addr_space)),
284 &self.const_usize(offset.bytes()),
288 if layout.primitive() != Pointer {
289 unsafe { llvm::LLVMConstPtrToInt(llval, llty) }
291 self.const_bitcast(llval, llty)
297 fn const_data_from_alloc(&self, alloc: ConstAllocation<'tcx>) -> Self::Value {
298 const_alloc_to_llvm(self, alloc)
303 layout: TyAndLayout<'tcx>,
304 alloc: ConstAllocation<'tcx>,
306 ) -> PlaceRef<'tcx, &'ll Value> {
307 let alloc_align = alloc.inner().align;
308 assert_eq!(alloc_align, layout.align.abi);
309 let llty = self.type_ptr_to(layout.llvm_type(self));
310 let llval = if layout.size == Size::ZERO {
311 let llval = self.const_usize(alloc_align.bytes());
312 unsafe { llvm::LLVMConstIntToPtr(llval, llty) }
314 let init = const_alloc_to_llvm(self, alloc);
315 let base_addr = self.static_addr_of(init, alloc_align, None);
318 llvm::LLVMRustConstInBoundsGEP2(
320 self.const_bitcast(base_addr, self.type_i8p()),
321 &self.const_usize(offset.bytes()),
325 self.const_bitcast(llval, llty)
327 PlaceRef::new_sized(llval, layout)
330 fn const_ptrcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value {
331 consts::ptrcast(val, ty)
335 /// Get the [LLVM type][Type] of a [`Value`].
336 pub fn val_ty(v: &Value) -> &Type {
337 unsafe { llvm::LLVMTypeOf(v) }
340 pub fn bytes_in_context<'ll>(llcx: &'ll llvm::Context, bytes: &[u8]) -> &'ll Value {
342 let ptr = bytes.as_ptr() as *const c_char;
343 llvm::LLVMConstStringInContext(llcx, ptr, bytes.len() as c_uint, True)
347 pub fn struct_in_context<'ll>(
348 llcx: &'ll llvm::Context,
353 llvm::LLVMConstStructInContext(llcx, elts.as_ptr(), elts.len() as c_uint, packed as Bool)
358 fn hi_lo_to_u128(lo: u64, hi: u64) -> u128 {
359 ((hi as u128) << 64) | (lo as u128)
362 fn try_as_const_integral(v: &Value) -> Option<&ConstantInt> {
363 unsafe { llvm::LLVMIsAConstantInt(v) }
366 pub(crate) fn get_dllimport<'tcx>(
370 ) -> Option<&'tcx DllImport> {
371 tcx.native_library(id)
372 .map(|lib| lib.dll_imports.iter().find(|di| di.name.as_str() == name))
376 pub(crate) fn is_mingw_gnu_toolchain(target: &Target) -> bool {
377 target.vendor == "pc" && target.os == "windows" && target.env == "gnu" && target.abi.is_empty()
380 pub(crate) fn i686_decorated_name(
381 dll_import: &DllImport,
383 disable_name_mangling: bool,
385 let name = dll_import.name.as_str();
387 let (add_prefix, add_suffix) = match dll_import.import_name_type {
388 Some(PeImportNameType::NoPrefix) => (false, true),
389 Some(PeImportNameType::Undecorated) => (false, false),
393 // Worst case: +1 for disable name mangling, +1 for prefix, +4 for suffix (@@__).
394 let mut decorated_name = String::with_capacity(name.len() + 6);
396 if disable_name_mangling {
397 // LLVM uses a binary 1 ('\x01') prefix to a name to indicate that mangling needs to be disabled.
398 decorated_name.push('\x01');
401 let prefix = if add_prefix && dll_import.is_fn {
402 match dll_import.calling_convention {
403 DllCallingConvention::C | DllCallingConvention::Vectorcall(_) => None,
404 DllCallingConvention::Stdcall(_) => (!mingw
405 || dll_import.import_name_type == Some(PeImportNameType::Decorated))
407 DllCallingConvention::Fastcall(_) => Some('@'),
409 } else if !dll_import.is_fn && !mingw {
410 // For static variables, prefix with '_' on MSVC.
415 if let Some(prefix) = prefix {
416 decorated_name.push(prefix);
419 decorated_name.push_str(name);
421 if add_suffix && dll_import.is_fn {
422 match dll_import.calling_convention {
423 DllCallingConvention::C => {}
424 DllCallingConvention::Stdcall(arg_list_size)
425 | DllCallingConvention::Fastcall(arg_list_size) => {
426 write!(&mut decorated_name, "@{}", arg_list_size).unwrap();
428 DllCallingConvention::Vectorcall(arg_list_size) => {
429 write!(&mut decorated_name, "@@{}", arg_list_size).unwrap();